1. Field of the Invention
The present invention relates to a cutting tooth, and more particularly, to a replaceable cutting tooth which can be removably attached to a cutting device such as a saw.
2. Description of Related Art
Tree fellers have become widely accepted as providing a fast and efficient means for harvesting trees. Such fellers typically include a mobile unit carrying a feller head. In operation, the mobile unit is driven up to a tree to be felled and the feller head moved into position adjacent the tree. Arms provided on the feller head grip the tree to support it during the felling operation. The base of the feller head is provided with a spinning disc saw which severs the tree. The feller head then supports the severed tree as it is transported to a new location for further operations, such as delimbing.
To maximize the amount of lumber available from each tree, it is desirable to sever the tree as cleanly as possible to avoid damage to nearby wood. In addition, it is desirable to sever the tree as near the ground as possible. These two goals are not always easily achieved. Sharp, undamaged saw teeth are important to cleanly sever the tree. However, in the process of maneuvering the feller saw to sever the tree as close to the ground as possible, it is not uncommon for the saw to inadvertently contact soil, boulders, and other low lying obstacles. Contact with soil and the like can be very abrasive and rapidly dull the saw teeth. In addition, contact of the spinning saw with boulders and small rocks can result in shock loads and other forces which break, chip, or dull the saw teeth. Such shock loads are particularly devastating to teeth made of brittle materials, such as carbide, which tend to shatter or crack.
Given the adverse conditions that the saws on feller heads are subject to, it is desirable that the saw teeth be durable, be able to withstand shock loads, and be easily and inexpensively replaceable when damaged or worn. A variety of saw teeth have been developed in an effort to meet these needs. For example, U.S. Pat. No. 4,738,291 to Isley shows a machined, circular cutting tooth which is attached to a tooth mount by a socket head bolt and nut. However, because this tooth is machined, it requires a great deal of labor to manufacture and, hence, is relatively expensive to produce. Further, the circular cutting edge is inefficient and the position of the socket head on the face of the tooth causes the socket to wear. Such wear can make removal and replacement of this type of tooth difficult.
Another tooth, shown in U.S. Pat. No. 4,932,447 to Morin, is square with a concave front cutting surface and a flat rear surface. An integral shaft extends from the rear surface allowing the tooth to be fixed to a saw. Similar, teeth are shown in U.S. Pat. Nos. 5,058,477, 5,085,112, and 5,088,371 to MacLennan. All of these teeth have an integral mounting shaft extending from the rear of the cutting tooth. As a result of this relatively complex shape, these types of teeth typically require a substantial amount of machining during the manufacturing process. The need for this labor intensive manufacturing technique makes such teeth relatively expensive. In addition, each time the tooth is replaced due to wear or damage, the mounting shaft must, inherently, also be replaced. The increased material necessary to make the mounting shaft further contributes to the expense of such teeth.